1. Field of the Invention
This invention relates to polymer blends comprising a polyalkylene terephthalate resin, an organopolysiloxane-polycarbonate block copolymer, and a calcium carbonate filler. The polymer blends have improved mechanical properties including improved warp and impact values.
2. Description of the Prior Art
Polyalkylene terephthalate resins are well-known to those skilled in the art--including their associated physical and chemical characteristics--as reported in numerous publications e.g. U.S. Pat. No. 2,465,319 (Whinfield et al.) issued Mar. 22, 1949; U.S. Pat. No. 3,047,539 (Pengilly) issued July 31, 1962; U.S. Pat. No. 3,859,246 (Jackson, Jr. et al.) issued Jan. 7, 1975; U.S. Pat. No. 4,043,971 (Wurmb et al.) issued Aug. 23, 1977; and the Encyclopedia of Polymer Science and Technology Vol. II, entitled Polyesters, pages 62-128, Interscience Publishers (1969), which publications are incorporated herein in their entirety by reference.
Organopolysiloxane-polycarbonate block copolymers are also well-known to those skilled in the art and are described in various U.S. and foreign patent applications including U.S. Pat. No. 3,821,325 (Merritt, Jr. et al.) issued June 28, 1974; U.S. Pat. No. 3,419,635 and U.S. Pat. No. 3,419,634 (both of Vaughn, Jr.) both issued Dec. 31, 1968; U.S. Pat. No. 3,832,419 (Merritt, Jr.) issued Aug. 27, 1974 and U.S. Pat. No. 3,189,662 (Vaughn, Jr.) issued June 15, 1965, among others.
Heretofore, to the best of the knowledge of applicants, blends of polyalkylene terephthalate resins and organopolysiloxane polycarbonate block copolymers containing calcium carbonate fillers having improved mechanical properties have not been reported by the prior art.